The proposed work is to increase our understanding of the role of pancreatic somatostatin in the normal and diabetic state. Somatostatin secretion will be assessed using the isolated perfused pancreases of dogs and chickens. The morphology of the various islet cell types and their distribution in various vertebrate classes will be studied. There will be on-going studies of somatostatin biosynthesis, and characterization of possible different molecular forms of somatostatin using various chromatographic techniques. Finally there is a project to evaluate the growth and development of the different cell types of the islet, and how these cells respond to chemical injury.